Analyses of agenda setting and decision making have highlighted that issue salience plays an important role in those stages of the policy process. This article investigates the role of issue salience in the implementation stage, focusing on transposition. We examine the extent to which issue salience - the relative importance attached to an issue in relation to others - influences the timeliness of transposing European Union directives in national legislation. We analyse 143 European Union environmental directives adopted in the period 1996-2008 in ten member states. We operationalize issue salience as the salience of hazardous substances and materials, salience for political parties in government and salience for the general public. Our results show faster transposition when environmental issues are salient for the governing political parties, Green political parties are included in the government, and the general public ranks environmental issues as a top priority.